Pelc S R, Viola-Magni M P
J Cell Biol. 1969 Aug;42(2):460-8. doi: 10.1083/jcb.42.2.460.
Italico rats were injected with thymidine-(3)H 6 hr after the end of 300 hr of intermittent cold treatment. This plan of experiment ensured replacement in the adrenal medulla of lost DNA which is specifically sensitive to cold treatment and has a labeling index sufficiently high for statistical evaluation. The labeling index in the adrenal medulla decreases to one-half of the initial value within 10 days in animals subjected to further intermittent cold treatment and within 32 days in animals kept at room temperature. The very low mitotic index and the absence of doubling of the labeling index show that the observed labeling cannot be ascribed to pre-mitotic DNA synthesis. The concept of metabolic DNA adequately explains the findings.
在间歇性冷处理300小时结束后6小时，给意大利大鼠注射胸腺嘧啶核苷 -（3）H。该实验方案确保了肾上腺髓质中对冷处理特别敏感且标记指数足够高以便进行统计学评估的丢失DNA的替换。在进一步接受间歇性冷处理的动物中，肾上腺髓质的标记指数在10天内降至初始值的一半，而在室温饲养的动物中则在32天内降至初始值的一半。极低的有丝分裂指数和标记指数没有翻倍表明观察到的标记不能归因于有丝分裂前的DNA合成。代谢性DNA的概念充分解释了这些发现。
